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Effect of Processing History on Fracture of Materials at High Strength Levels

D. R. PoirierM. L. EbnerMerton C. FlemingsW. A. Backofen

出版	Air Force Materials Laboratory, Aeronautical Systems Division, Air Force Systems Command, United States Air Force, 1963
URL	http://books.google.com.hk/books?id=zRHmNwAACAAJ&hl=&source=gbs_api

註釋The influence of melting and solidification variables on the fracture toughness of AISI 4340 steel at a yield strength of 240,000 psi was studied. In this initial part of the program, four different ingot structures were obtained by casting air-melted 4340 steel into four different types of molds: (1) a sand mold, (2) a cast iron chill mold, (3) a 'hot' mold lined with exothermic material, and (4) a mold producing unidirectional solidification. Ingots of these structures were evaluated as described below, as were comparable vacuum cast ingot of types (1) and (4). All material tested (air-melted and cast) had a fracture toughness typical of air-melted AISI 4340 steel but inferior to the best quality vacuum melted steel of this type. It is concluded that vacuum melting and casting per se under some conditions greatly improve the fracture toughness of the steel produced. (Author).